Wooden structural elements, such as utility poles, posts or the like, are often damaged by rot and decay when exposed to the elements over a period of time. My U.S. Pat. No. 4,905,441, issued Mar. 6, 1990, makes note of the fact that woodpeckers are a substantial contributing factor to rot and decay of wood poles, creating void spaces within the interior of the poles they attack surrounded by rotten or deteriorating wood.
Quite a number of techniques have been employed in an attempt to strengthen deteriorated or rotten wood poles and the like. For example, non-foaming epoxies and polymers have been injected into the rotten portion. This approach has been less than successful because, among other things, the injected materials have been too viscous to penetrate the deteriorated wood. Thus, oxygen, which is a necessary contributing factor to wood rot (along with moisture and micro-organisms) can still reach the rotted area, and decay continues.
U.S. Pat. No. 4,905,441 discloses a system utilized to strengthen a structural element, such as a woodpecker-damaged wood pole. According to the patented method, structural foaming agent is inserted into the void space in an essentially unfoamed state. After the inserting step, a flexible container is positioned in the passageway leading from the exterior of the structural element to the void space, the flexible container having structural foaming agent therein.
The passageway is sealed by foaming the structural foaming agent within the flexible container to form a bond between the flexible container and the structural element at the location of the passageway.
The void space is then substantially filled after the step of sealing the passageway by foaming and expanding the structural foaming agent within the void space.
While the system disclosed in U.S. Pat. No. 4,905,441 is quite adequate for its intended purpose, it does have some drawbacks. First of all, utilizing the prior art system just described only a relatively small percentage of the decayed or rotten wood defining the void space is penetrated by the structural foaming agent. This is due to the fact that relatively little pressure is developed by the structural foaming agent during foaming thereof. Furthermore, utilization of a foaming agent-filled bag to seal the passageway requires significant time and effort. It has also been found that the foaming agent extruded through the bag does not penetrate the rotten or decayed wood surrounding the passageway to as great a degree as desireable.